Recommended for

Pedestrians walk area with at least 3 m width.

Areas where storm water drainage line or ducts are not present below the pedestrian walk.

Rainfall up to 800 mm.

Methodology

In the central part of the pedestrian walk select an area of 2 m x 2 m. (L x W). If non-porous paver blocks are installed, then remove these paver blocks within the selected 2 m x 2 m area.

If black dust is present in it, then remove it completely. If a pure gravel layer is present, then do not remove it.

Drill one shot hole of 2” to 3” diameter and up to 20’ depth using a hand operated drilling machine, within the center of 2 m x 2 m area

Immediately insert a perforated PVC pipe of 2” diameter in the hole. Keep the height of this pipe 1” below the pedestrian walk. Fill the pipe with washed clean equigranular sand. Close the PVC pipe with a PVC cap.

Replace the black dust with a pure gravel bed up to a thickness of 6”. If a gravel layer is already present, then remove the upper 1” layer. Wash it and clean it and top it up after drying.

Replace the non-porous paver blocks by 100% porous paver blocks of the same size within 2 m x 2 m of area. Maintain the level of the porous block with the adjoining non-porous blocks. This will help to recharge around 2000 lits of rainwater from an average rainfall of 800 mm within monsoon months.

Replicate this design within the pedestrian walk at least up to a stretch of 50 m length.

After 5 m interval the same design can be replicated for another 50 m stretch.

Process

The rainfall falling over this porous surface of 2 m x 2 m area will seep down due to the raindrop intensity.

It will get stored in the gravel bed. As soon as the gravel bed gets saturated with water the water will start seeping into the shot hole.

Through the shot hole it will go down and start recharging the murum or the weathered material present over the aquifer.

Precautions

If a storm water drainage line or any other duct is passing below the pedestrian walk, then do not select that area for this project.

During the rainy season try to keep this project area clean. This will help in enhancing the seepage rate from the porous pavements.

Cleaning will not allow the dust to get stored within the joints of the paver blocks.

The porous paver blocks will not pass the dust, clay, silt etc present in the stormwater and the shot holes will be protected from clogging.

Immediately after the floods clean the upper surface of the paver blocks using pressurised water to reinstate their perviousness.

Do not allow parking of vehicles or hawkers to stand within the project area.

Maintenance

This structure is usually constructed in the public areas. Hence it is necessary to maintain the cleanliness over the pedestrian walk throughout the year.

Display a board showing the details of the project so that the community will also take care of it.